Canopy landing structure



July 22, 1969 w. H. WAINWRIGHT CANOPY LANDNG STRUCTURE s sheets-sheet 1Filed rpril 4, 1967 INVENTOR. WILLIAM H. WAINWRIGHT FIGZ July 22, 1969w. H. wAnNwRlGH-r 3,456,909

CANOPY LANDNG STRUCTURE Filed April 4,1967 v 5 sheets-sheet 2' INVENTOR.WILLIAM H. WAINWRIGHT July 22, 1969 w. H. wAlNwRlGHT 3,456,909

CANOPY LANDING STRUCTURE Filed April 4, 1967 3 SheetS-Sheet- INVENTOR.WILLIAM H. WAI NWRIGHT TM mum United States Patent Oflce 3,456,909CANOPY LANDING STRUCTURE William H. Wainwright, 61 Highland St.,Cambridge, Mass. 02138 Filed Apr. 4, 1967, Ser. No. 628,476 Int. Cl.B641 00 U.S. Cl. 244-114 9 Claims ABSTRACT OF THE DISCLOSURE A landingstructure for airborne vehicles, personnel and material which can lbeused on the natural canopy formed by, tree tops, vines, bushes andsimilar ground cover. One or more tension nets are spread on top of thecanopy to gather enough vertical reaction from the underlying groundcover to Support the required load. A rigid, skeletal space frame ispositioned on the load receiving portion of the tension nets to providea stable, substantially horizontal support for a landing platform thatis secured to the frame. The platform can be a wire mesh net for landingpersonnel and small equipment or a solid platform to permit the landingof helicopters and heavy materiel.

Background of the invention This invention relates to landing structuresfor airborne vehicles, personnel and materiel and, more particularly, toa landing structure which can be used in areas where the natural groundcover precludes an initial ground landing by the airborne vehicle.

In many parts of the World, the natural ground cover is suiciently denseor otherwise structured to prevent helicopters from landing on theground. Typical examples of such areas are found in the rain forests[and jungles of the equatorial zone and the deciduous forests of thetemperate zones. It is often desirable in such areas to olf load and onload personnel and equipment either for military or commercial purposes.In addition, a temporary landing site is generally needed during thetime required for the olf-loaded ground personnel to clear a suflicientland area to provide a permanent ground level landing site.

It is accordingly a general object of the present invention to provide alanding structure that can be airlifted to a remote landing site andthen placed upon the local ground cover canopy to form a landingstructure for airborne vehicles, personnel and materiel.

'It is a specific object of the present invention to provide a canopylanding structure that will support relatively heavy loads with aminimum number of structural components.

It is another object of the present invention to provide an extremelylightweight landing `structure that can be assembled into a few majorcomponents at a convenient location and then airlifted to the desiredlanding site where the components can be put together by a small numberof personnel.

In the accomplishment of these objects, I employ one or more resilient,locally deformable, tension nets that can be airlifted to the la-ndingsite and then deployed on top of the ground cover canopy to form acentral load receiving area and two or more opposed load distributingareas. If desired, a separate space frame having a suitable platform canbe placed on the load receiving portion of the net or nets to provide astable platform for helicopters, personnel and equipment.

Patented July 22, 1969 selected for purposes of illustration, and shownin the accompanying drawings.

Brief description of the several Views of the drawings FIGURE 1 is aview in perspective showing the deployment of two airlifted tension netsof the present invention on a tree top canopy and a space frame platformabout to be deposited on the crossed nets;

FIGURE 2 is an enlarged plan view of a portion of one of the tensionnets shown in FIGURE 1;

FIGURE 3 is a plan view of the space frame shown in FIGURE 1;

FIGURE 4 is a side elevation of the space frame shown in FIGURE 3; and

FIGURE 5 is a plan view of an alternate embodiment of the presentinvention utilizing a star shaped tension net and showing a helicopterresting on the space frame platform.

Description of the preferred embodiments Turning now to the drawings andparticularly to FIG- URE 1 thereof, there is shown in perspective view,a representative example of the deployment of the landing structure ofthe present invention, indicated generally by the reference numeral 10,on a ground cover canopy 12 by three airborne helicopters 14, 16 and 18.As shown in FIGURE 1, the first helicopter 14 has already d-eployed onetension net 20 on top of the ground cover canopy 12. The secondhelicopter 16 is shown in the process of laying down another tension net22 from a reel type net carrier 24. After the two tension nets 20 and 22have been laid down in a crossed configuration, the third helicopter 18deposits a skeletal, rigid, spaced frame and landing platform, indicatedgenerally as 26, on the crossed portion of the nets. Thereafter, men arelanded on the nets to position and secure the space frame landingplatform 26 for subsequent use by the helicopters as a helipad.

Having briefly described a typical deployment of the canopy landingstructure 10, it will now be helpful to examine in detail the majorstructural components thereof. In its basic form, the present inventioncomprises a single tension net, for example, net 20 shown generally inFIGURE l and in greater detail in FIGURE 2. The purpose of the net isthreefold: first to gather enough vertical reaction and horizontalsupport from the tree tops or canopy to both support and stabilize therequired load including the space frame platform 26, if one is employed;second, to provide an extension of the platform which will suppress theadjacent tree tops and provide clearance for helicopter rotors; and,third, to provide a safety net for personnel.

Preferably, the net is fabricated from a wire' rope 28 that is joined atintersections by suitable clamps or swaging sleeves 30 as shown inFIGURE 2. Wire clips 32 are used to secure the wire ropes whenever theropes do not cross, as for example, along the outer longitudinal ropeswhich form the sides of the tension net. For the net dimensions anddesign loads hereinafter described, it had been found that a wire ropeof 7 x 19 galvanized aircord type; U.S. military specifications: cablesteel (carbon) flexible, preformed MIL-W-15llA is satisfactory.

The particular grid pattern of the net with 90 intersections has beenfound to provide a stronger and more 3 easily deployed net than the morecommonly used fabrication technique of joining wires parallel to eachother. This type of construction produces a resilient and locallydeformable net that will readily conform to the complex topologicalfeatures of the ground cover canopy 12. Since the net 20 is undertension in its operative position, it can be described from a functionalstandpoint as having a load receiving portion and at least two loaddistributing portions, identified by the reference numerals 20a and20h-20c, respectively, in FIGURES 1 and 2.

Looking at these figures, it can be seen that the central load receivingportion 20a has much liner wire mesh than the end sections or loaddistributing portions 2Gb and 20c. For a design load of 10,000 lbs., thetension net 20 would typically have exterior dimensions of 250 ft. by-20 ft. Given these dimensions, each load distributing portion isapproximately 90 feet long and the center section or load receivingportion is 60 ft. long. The grid pattern within each of the end loaddistributing portions has a nominal dimension of 2.5 ft. x 2.5 ft.square while the grid pattern within the central load receiving portionhas a nominal dimension of 0.5 ft. x 0.5 ft. square thus producing a 5:1size ratio.

It should be understood that the above dimensions are merelyillustrative of a particular configuration and design load and,therefore, should not be construed as limiting the scope of the presentinvention. Furthermore, although the use of different mesh dimensionsfor the load receiving portion and the load distributing portions ispreferred, it is not absolutely essential since a single mesh dimensioncan be employed for the entire net. It will therefore be apparent tothose skilled in the art that the basic concept herein described is acanopy landing structure comprising at least one resilient, locallydeformable tension net having a load receiving portion and a pluralityof load distributing portions.

In order to facilitate the deployment of the tension net and maintainthe net in a spread condition, a number of telescoping, transversespreaders 34 are provided in each portion of the net. The spreaders 34are made to telescope so that they can be used with nets of varyingwidths thereby greatly reducing the number of individual componentswhich must be stockpiled and moved through the supply pipeline.

Looking at FIGURE 2, the distal end of the tension net is provided witha grapnel 36 which engages the tree tops or other ground cover and helpsto uncoil the net from the reel mechanism 24 as shown in FIG- URE l. Ofcourse, other systems, such as an accordion folding of the net or anexplosive charge can be used to assist in deploying the tension net overthe ground cover.

One of the advantages of the present invention is its inherentflexibility to accommodate various design loads and stabilityrequirements. For example, in its simplest form, a single small net canbe used for disembarking troops. If slightly greater loads are to behandled, additional nets can be added with the load receiving portionsof each net assembled in superposed relation as shown in FIGURE l. Thenext step up in strength and stability is the addition of a simple,single layer, rigid platform which provides a stable base for unloadingequipment, mounting Winches, etc. This platform has not been depicted byitself in the drawings because it forms an integral part of the nextstep up in stability and strength. At this point, an additional surfaceplatform is added with leveling legs using the rst platform as a base.Collectively, this structure defines the previously mentioned rigid,skeletal space frame and platform 26 shown generally in FIGURE l and ingreater detail in the plan and side elevational views of FIGURES 3 and 4respectively.

Referring to FIGS. 3 and 4, the space frame and platform 26 comprises atriangular base formed from three tubular members 38 and a hexagonalplatform support constructed from six tubular members 40 that aresecured together by keystone fasteners 42. The triangular base membersand hexagonal platform support members are held in parallel, planarrelation by a plurality of connecting members 44 which are secured atone end to the keystone fasteners 42 and at the other end by tie plates46 mounted on three vertical tubular supports 48. Threadably engagedwithin each tubular support 48 is a leveling leg 50 that terminates in apivotally mounted leveling pad 52. Leveling pad 52 has a generallyinverted trough-shape with serrated edges to grip the tension net whenthe space frame is lowered onto the net by helicopter 18 as shown inFIG. 1.

The skeletal, hexogonal frame formed by members 40 provides a supportfor a suitable platform, such as, a relative ne mesh net 54. The net 54can be fabricated from wire or other materials including ordinary hemprope and nylon or other synthetic materials. Alternatively, a solidcontinuous platform, formed for example from aluminum skinned sandwichpanels, can be mounted on the hexagonal support to provide a landingplatform for helicopters and a loading platform for heavy equipment.

Although the description of the canopy landing structure of the presentinvention has so far been limited to nets having a generally rectangularshape, it should be understood that the invention is not restricted tosuch configuration. For example, an alternate embodiment of the presentinvention is illustrated in FIGURE 5 wherein a tension net 56 has agenerally star-shaped configuration. In this embodiment, the centralload receiving portion 56a comprises a circular area while the loaddistributing portions 56b are formed generally by the six points of thestan Having described in detail the preferred embodiment of the presentinvention, it will now be apparent to those skilled in the art thatnumerous modifications can be made without departing from the scope ofthe invention.

For example, a single platform layer, pneumatic cushion, or otherstructure can be positioned on the load receiving portion of the net inplace of the space frame. Additionally, it should be understood that incertain topological situations where the load receiving portion ispositioned on top of a tree, the load distributing portions of the netmay function substantially as guys for the central load receivingportion.

What I claim is:

1. A canopy landing structure comprising: a plurality of resilient,locally deformable tension nets each having a load receiving portion anda plurality of load distributing portions, said nets assembled with onlythe load receiving portions thereof in superposed relation.

2. A canopy landing structure comprising: at least one resilient,locally deformable tension net having a load receiving portion and aplurality of load distributing portions, said load receiving portionhaving a `liner mesh than said load distributing portions.

3. A canopy landing structure comprising: at least one resilient,locally deformable tension net having a substantially star-shapedconfiguration with the center of the star-shaped net forming the loadreceiving portion and the star points forming the load distributingportions.

4. A canopy landing structure comprising: at least one resilient,locally deformable tension net having a load receiving portion and aplurality of load distributing portions; and, a rigid, space framepositioned on said tension net in the load receiving portion thereof.

5. The structure of claim 4 further characterized by said space framehaving a triangular base, a hexagonal platform support andinterconnecting means for maintaining said base and platform support inplanar, parallel relation.

6. The structure of claim 5 further characterized by a platform securedto said hexagonal platform support.

7. The structure of claim 6 wherein said platform comprises a net.

5 6 `8. The structure of claim 6 wherein said platform com- FOREIGNPATENTS 475,066 10/1952 Italy.

prises a continuous structure.

9. The structure of claim 4 further characterized by means for levelingsaid space frame.

OTHER REFERENCES References Cited 5 Science News, Helicopter Unloads onTreetops, 891250,

. 6, UNITED STATES PATENTS Apr 9 196 P 250mm "n 9/ 1957 Hawkins et al,244-114 MILTON BUCHLER, Primary Examiner 6/1962 Grundy 244114 PAUL E.SAUBERER A 't t E amine 7/1963 Oestrich 244-114 10 Ss an X r 9/1964Laufer 244-114

